Warn, don't error, on missing PKs in schema

Fixes #3251

api/src/middleware/schema.ts

@@ -1,9 +1,20 @@
 import { RequestHandler } from 'express';
 import asyncHandler from 'express-async-handler';
 import { schemaInspector } from '../database';
+import logger from '../logger';
 
 const getSchema: RequestHandler = asyncHandler(async (req, res, next) => {
 	const schemaOverview = await schemaInspector.overview();
+
+	for (const [collection, info] of Object.entries(schemaOverview)) {
+		if (!info.primary) {
+			logger.warn(
+				`Collection "${collection}" doesn't have a primary key column and will be ignored`
+			);
+			delete schemaOverview[collection];
+		}
+	}
+
 	req.schema = schemaOverview;
 
 	return next();